From b50eba7e2d534762a19a7207dda012f09302a8d2 Mon Sep 17 00:00:00 2001 From: Richard Guy Briggs Date: Mon, 16 Sep 2013 18:20:42 -0400 Subject: audit: format user messages to size of MAX_AUDIT_MESSAGE_LENGTH Messages of type AUDIT_USER_TTY were being formatted to 1024 octets, truncating messages approaching MAX_AUDIT_MESSAGE_LENGTH (8970 octets). Set the formatting to 8560 characters, given maximum estimates for prefix and suffix budgets. See the problem discussion: https://www.redhat.com/archives/linux-audit/2009-January/msg00030.html And the new size rationale: https://www.redhat.com/archives/linux-audit/2013-September/msg00016.html Test ~8k messages with: auditctl -m "$(for i in $(seq -w 001 820);do echo -n "${i}0______";done)" Reported-by: LC Bruzenak Reported-by: Justin Stephenson Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- include/uapi/linux/audit.h | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 75cef3fd97ad..5dfcd85037e2 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -358,6 +358,12 @@ enum { #define AUDIT_PERM_READ 4 #define AUDIT_PERM_ATTR 8 +/* MAX_AUDIT_MESSAGE_LENGTH is set in audit:lib/libaudit.h as: + * 8970 // PATH_MAX*2+CONTEXT_SIZE*2+11+256+1 + * max header+body+tailer: 44 + 29 + 32 + 262 + 7 + pad + */ +#define AUDIT_MESSAGE_TEXT_MAX 8560 + struct audit_status { __u32 mask; /* Bit mask for valid entries */ __u32 enabled; /* 1 = enabled, 0 = disabled */ -- cgit v1.2.3-71-gd317 From 42f74461a5b60cf6b42887e6d2ff5b7be4abf1ca Mon Sep 17 00:00:00 2001 From: Richard Guy Briggs Date: Mon, 20 May 2013 15:08:18 -0400 Subject: audit: change decimal constant to macro for invalid uid SFR reported this 2013-05-15: > After merging the final tree, today's linux-next build (i386 defconfig) > produced this warning: > > kernel/auditfilter.c: In function 'audit_data_to_entry': > kernel/auditfilter.c:426:3: warning: this decimal constant is unsigned only > in ISO C90 [enabled by default] > > Introduced by commit 780a7654cee8 ("audit: Make testing for a valid > loginuid explicit") from Linus' tree. Replace this decimal constant in the code with a macro to make it more readable (add to the unsigned cast to quiet the warning). Cc: Stephen Rothwell Cc: "Eric W. Biederman" Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- include/uapi/linux/audit.h | 2 ++ kernel/auditfilter.c | 2 +- 2 files changed, 3 insertions(+), 1 deletion(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 5dfcd85037e2..c1f0fced3ede 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -380,6 +380,8 @@ struct audit_tty_status { __u32 log_passwd; /* 1 = enabled, 0 = disabled */ }; +#define AUDIT_UID_UNSET (unsigned int)-1 + /* audit_rule_data supports filter rules with both integer and string * fields. It corresponds with AUDIT_ADD_RULE, AUDIT_DEL_RULE and * AUDIT_LIST_RULES requests. diff --git a/kernel/auditfilter.c b/kernel/auditfilter.c index f7aee8be7fb2..8a344cebd8bf 100644 --- a/kernel/auditfilter.c +++ b/kernel/auditfilter.c @@ -423,7 +423,7 @@ static struct audit_entry *audit_data_to_entry(struct audit_rule_data *data, f->lsm_rule = NULL; /* Support legacy tests for a valid loginuid */ - if ((f->type == AUDIT_LOGINUID) && (f->val == ~0U)) { + if ((f->type == AUDIT_LOGINUID) && (f->val == AUDIT_UID_UNSET)) { f->type = AUDIT_LOGINUID_SET; f->val = 0; } -- cgit v1.2.3-71-gd317 From b0fed40214ce79ef70d97584ebdf13f89786da0e Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Wed, 22 May 2013 12:54:49 -0400 Subject: audit: implement generic feature setting and retrieving The audit_status structure was not designed with extensibility in mind. Define a new AUDIT_SET_FEATURE message type which takes a new structure of bits where things can be enabled/disabled/locked one at a time. This structure should be able to grow in the future while maintaining forward and backward compatibility (based loosly on the ideas from capabilities and prctl) This does not actually add any features, but is just infrastructure to allow new on/off types of audit system features. Signed-off-by: Eric Paris Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- include/linux/audit.h | 2 + include/uapi/linux/audit.h | 16 +++++++ kernel/audit.c | 109 +++++++++++++++++++++++++++++++++++++++++++++ 3 files changed, 127 insertions(+) (limited to 'include/uapi/linux') diff --git a/include/linux/audit.h b/include/linux/audit.h index 729a4d165bcc..7b31bec9bccb 100644 --- a/include/linux/audit.h +++ b/include/linux/audit.h @@ -73,6 +73,8 @@ struct audit_field { void *lsm_rule; }; +extern int is_audit_feature_set(int which); + extern int __init audit_register_class(int class, unsigned *list); extern int audit_classify_syscall(int abi, unsigned syscall); extern int audit_classify_arch(int arch); diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index c1f0fced3ede..9eddf2ca614f 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -68,6 +68,9 @@ #define AUDIT_MAKE_EQUIV 1015 /* Append to watched tree */ #define AUDIT_TTY_GET 1016 /* Get TTY auditing status */ #define AUDIT_TTY_SET 1017 /* Set TTY auditing status */ +#define AUDIT_SET_FEATURE 1018 /* Turn an audit feature on or off */ +#define AUDIT_GET_FEATURE 1019 /* Get which features are enabled */ +#define AUDIT_FEATURE_CHANGE 1020 /* audit log listing feature changes */ #define AUDIT_FIRST_USER_MSG 1100 /* Userspace messages mostly uninteresting to kernel */ #define AUDIT_USER_AVC 1107 /* We filter this differently */ @@ -375,6 +378,19 @@ struct audit_status { __u32 backlog; /* messages waiting in queue */ }; +struct audit_features { +#define AUDIT_FEATURE_VERSION 1 + __u32 vers; + __u32 mask; /* which bits we are dealing with */ + __u32 features; /* which feature to enable/disable */ + __u32 lock; /* which features to lock */ +}; + +#define AUDIT_LAST_FEATURE -1 + +#define audit_feature_valid(x) ((x) >= 0 && (x) <= AUDIT_LAST_FEATURE) +#define AUDIT_FEATURE_TO_MASK(x) (1 << ((x) & 31)) /* mask for __u32 */ + struct audit_tty_status { __u32 enabled; /* 1 = enabled, 0 = disabled */ __u32 log_passwd; /* 1 = enabled, 0 = disabled */ diff --git a/kernel/audit.c b/kernel/audit.c index 74550ff3644f..29ee6a421c6c 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -139,6 +139,15 @@ static struct task_struct *kauditd_task; static DECLARE_WAIT_QUEUE_HEAD(kauditd_wait); static DECLARE_WAIT_QUEUE_HEAD(audit_backlog_wait); +static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION, + .mask = -1, + .features = 0, + .lock = 0,}; + +static char *audit_feature_names[0] = { +}; + + /* Serialize requests from userspace. */ DEFINE_MUTEX(audit_cmd_mutex); @@ -583,6 +592,8 @@ static int audit_netlink_ok(struct sk_buff *skb, u16 msg_type) return -EOPNOTSUPP; case AUDIT_GET: case AUDIT_SET: + case AUDIT_GET_FEATURE: + case AUDIT_SET_FEATURE: case AUDIT_LIST_RULES: case AUDIT_ADD_RULE: case AUDIT_DEL_RULE: @@ -627,6 +638,94 @@ static int audit_log_common_recv_msg(struct audit_buffer **ab, u16 msg_type) return rc; } +int is_audit_feature_set(int i) +{ + return af.features & AUDIT_FEATURE_TO_MASK(i); +} + + +static int audit_get_feature(struct sk_buff *skb) +{ + u32 seq; + + seq = nlmsg_hdr(skb)->nlmsg_seq; + + audit_send_reply(NETLINK_CB(skb).portid, seq, AUDIT_GET, 0, 0, + &af, sizeof(af)); + + return 0; +} + +static void audit_log_feature_change(int which, u32 old_feature, u32 new_feature, + u32 old_lock, u32 new_lock, int res) +{ + struct audit_buffer *ab; + + ab = audit_log_start(NULL, GFP_KERNEL, AUDIT_FEATURE_CHANGE); + audit_log_format(ab, "feature=%s new=%d old=%d old_lock=%d new_lock=%d res=%d", + audit_feature_names[which], !!old_feature, !!new_feature, + !!old_lock, !!new_lock, res); + audit_log_end(ab); +} + +static int audit_set_feature(struct sk_buff *skb) +{ + struct audit_features *uaf; + int i; + + BUILD_BUG_ON(AUDIT_LAST_FEATURE + 1 > sizeof(audit_feature_names)/sizeof(audit_feature_names[0])); + uaf = nlmsg_data(nlmsg_hdr(skb)); + + /* if there is ever a version 2 we should handle that here */ + + for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { + u32 feature = AUDIT_FEATURE_TO_MASK(i); + u32 old_feature, new_feature, old_lock, new_lock; + + /* if we are not changing this feature, move along */ + if (!(feature & uaf->mask)) + continue; + + old_feature = af.features & feature; + new_feature = uaf->features & feature; + new_lock = (uaf->lock | af.lock) & feature; + old_lock = af.lock & feature; + + /* are we changing a locked feature? */ + if ((af.lock & feature) && (new_feature != old_feature)) { + audit_log_feature_change(i, old_feature, new_feature, + old_lock, new_lock, 0); + return -EPERM; + } + } + /* nothing invalid, do the changes */ + for (i = 0; i <= AUDIT_LAST_FEATURE; i++) { + u32 feature = AUDIT_FEATURE_TO_MASK(i); + u32 old_feature, new_feature, old_lock, new_lock; + + /* if we are not changing this feature, move along */ + if (!(feature & uaf->mask)) + continue; + + old_feature = af.features & feature; + new_feature = uaf->features & feature; + old_lock = af.lock & feature; + new_lock = (uaf->lock | af.lock) & feature; + + if (new_feature != old_feature) + audit_log_feature_change(i, old_feature, new_feature, + old_lock, new_lock, 1); + + if (new_feature) + af.features |= feature; + else + af.features &= ~feature; + af.lock |= new_lock; + } + + return 0; +} + static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) { u32 seq; @@ -698,6 +797,16 @@ static int audit_receive_msg(struct sk_buff *skb, struct nlmsghdr *nlh) if (status_get->mask & AUDIT_STATUS_BACKLOG_LIMIT) err = audit_set_backlog_limit(status_get->backlog_limit); break; + case AUDIT_GET_FEATURE: + err = audit_get_feature(skb); + if (err) + return err; + break; + case AUDIT_SET_FEATURE: + err = audit_set_feature(skb); + if (err) + return err; + break; case AUDIT_USER: case AUDIT_FIRST_USER_MSG ... AUDIT_LAST_USER_MSG: case AUDIT_FIRST_USER_MSG2 ... AUDIT_LAST_USER_MSG2: -- cgit v1.2.3-71-gd317 From d040e5af380554c23ffe0a034ae5f3e53da93a1d Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Fri, 24 May 2013 09:18:04 -0400 Subject: audit: audit feature to only allow unsetting the loginuid This is a new audit feature which only grants processes with CAP_AUDIT_CONTROL the ability to unset their loginuid. They cannot directly set it from a valid uid to another valid uid. The ability to unset the loginuid is nice because a priviledged task, like that of container creation, can unset the loginuid and then priv is not needed inside the container when a login daemon needs to set the loginuid. Signed-off-by: Eric Paris Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- include/uapi/linux/audit.h | 3 ++- kernel/audit.c | 3 ++- kernel/auditsc.c | 3 +++ 3 files changed, 7 insertions(+), 2 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 9eddf2ca614f..05e5e8fc2ac4 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -386,7 +386,8 @@ struct audit_features { __u32 lock; /* which features to lock */ }; -#define AUDIT_LAST_FEATURE -1 +#define AUDIT_FEATURE_ONLY_UNSET_LOGINUID 0 +#define AUDIT_LAST_FEATURE AUDIT_FEATURE_ONLY_UNSET_LOGINUID #define audit_feature_valid(x) ((x) >= 0 && (x) <= AUDIT_LAST_FEATURE) #define AUDIT_FEATURE_TO_MASK(x) (1 << ((x) & 31)) /* mask for __u32 */ diff --git a/kernel/audit.c b/kernel/audit.c index 29ee6a421c6c..fbfa3a74decb 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -144,7 +144,8 @@ static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION, .features = 0, .lock = 0,}; -static char *audit_feature_names[0] = { +static char *audit_feature_names[1] = { + "only_unset_loginuid", }; diff --git a/kernel/auditsc.c b/kernel/auditsc.c index c75d7813aef2..924c0bf048d2 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1974,6 +1974,9 @@ static int audit_set_loginuid_perm(kuid_t loginuid) /* it is set, you need permission */ if (!capable(CAP_AUDIT_CONTROL)) return -EPERM; + /* reject if this is not an unset and we don't allow that */ + if (is_audit_feature_set(AUDIT_FEATURE_ONLY_UNSET_LOGINUID) && uid_valid(loginuid)) + return -EPERM; return 0; } -- cgit v1.2.3-71-gd317 From 21b85c31d23f2047d47e1f74bfa5caa8b75c1c77 Mon Sep 17 00:00:00 2001 From: Eric Paris Date: Thu, 23 May 2013 14:26:00 -0400 Subject: audit: audit feature to set loginuid immutable This adds a new 'audit_feature' bit which allows userspace to set it such that the loginuid is absolutely immutable, even if you have CAP_AUDIT_CONTROL. Signed-off-by: Eric Paris Signed-off-by: Richard Guy Briggs Signed-off-by: Eric Paris --- include/uapi/linux/audit.h | 3 ++- kernel/audit.c | 3 ++- kernel/auditsc.c | 3 +++ 3 files changed, 7 insertions(+), 2 deletions(-) (limited to 'include/uapi/linux') diff --git a/include/uapi/linux/audit.h b/include/uapi/linux/audit.h index 05e5e8fc2ac4..e2f0d9977131 100644 --- a/include/uapi/linux/audit.h +++ b/include/uapi/linux/audit.h @@ -387,7 +387,8 @@ struct audit_features { }; #define AUDIT_FEATURE_ONLY_UNSET_LOGINUID 0 -#define AUDIT_LAST_FEATURE AUDIT_FEATURE_ONLY_UNSET_LOGINUID +#define AUDIT_FEATURE_LOGINUID_IMMUTABLE 1 +#define AUDIT_LAST_FEATURE AUDIT_FEATURE_LOGINUID_IMMUTABLE #define audit_feature_valid(x) ((x) >= 0 && (x) <= AUDIT_LAST_FEATURE) #define AUDIT_FEATURE_TO_MASK(x) (1 << ((x) & 31)) /* mask for __u32 */ diff --git a/kernel/audit.c b/kernel/audit.c index fbfa3a74decb..f3f36f5eb4ae 100644 --- a/kernel/audit.c +++ b/kernel/audit.c @@ -144,8 +144,9 @@ static struct audit_features af = {.vers = AUDIT_FEATURE_VERSION, .features = 0, .lock = 0,}; -static char *audit_feature_names[1] = { +static char *audit_feature_names[2] = { "only_unset_loginuid", + "loginuid_immutable", }; diff --git a/kernel/auditsc.c b/kernel/auditsc.c index 924c0bf048d2..63223d671a6e 100644 --- a/kernel/auditsc.c +++ b/kernel/auditsc.c @@ -1971,6 +1971,9 @@ static int audit_set_loginuid_perm(kuid_t loginuid) /* if we are unset, we don't need privs */ if (!audit_loginuid_set(current)) return 0; + /* if AUDIT_FEATURE_LOGINUID_IMMUTABLE means never ever allow a change*/ + if (is_audit_feature_set(AUDIT_FEATURE_LOGINUID_IMMUTABLE)) + return -EPERM; /* it is set, you need permission */ if (!capable(CAP_AUDIT_CONTROL)) return -EPERM; -- cgit v1.2.3-71-gd317